mirror of
https://github.com/scratchfoundation/scratch-blocks.git
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132 lines
3.9 KiB
JavaScript
132 lines
3.9 KiB
JavaScript
/**
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* @license
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* Visual Blocks Editor
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*
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* Copyright 2017 Google Inc.
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* https://developers.google.com/blockly/
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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* @fileoverview Methods for dragging a workspace visually.
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* @author fenichel@google.com (Rachel Fenichel)
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*/
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'use strict';
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goog.provide('Blockly.WorkspaceDragger');
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goog.require('goog.math.Coordinate');
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goog.require('goog.asserts');
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/**
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* Class for a workspace dragger. It moves the workspace around when it is
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* being dragged by a mouse or touch.
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* Note that the workspace itself manages whether or not it has a drag surface
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* and how to do translations based on that. This simply passes the right
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* commands based on events.
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* @param {!Blockly.WorkspaceSvg} workspace The workspace to drag.
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* @constructor
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*/
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Blockly.WorkspaceDragger = function(workspace) {
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/**
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* @type {!Blockly.WorkspaceSvg}
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* @private
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*/
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this.workspace_ = workspace;
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/**
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* The workspace's metrics object at the beginning of the drag. Contains size
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* and position metrics of a workspace.
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* Coordinate system: pixel coordinates.
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* @type {!Object}
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* @private
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*/
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this.startDragMetrics_ = workspace.getMetrics();
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/**
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* The scroll position of the workspace at the beginning of the drag.
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* Coordinate system: pixel coordinates.
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* @type {!goog.math.Coordinate}
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* @private
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*/
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this.startScrollXY_ = new goog.math.Coordinate(
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workspace.scrollX, workspace.scrollY);
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};
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/**
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* Sever all links from this object.
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* @package
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*/
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Blockly.WorkspaceDragger.prototype.dispose = function() {
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this.workspace_ = null;
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};
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/**
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* Start dragging the workspace.
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* @package
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*/
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Blockly.WorkspaceDragger.prototype.startDrag = function() {
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if (Blockly.selected) {
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Blockly.selected.unselect();
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}
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this.workspace_.setupDragSurface();
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};
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/**
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* Finish dragging the workspace and put everything back where it belongs.
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* @param {!goog.math.Coordinate} currentDragDeltaXY How far the pointer has
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* moved from the position at the start of the drag, in pixel coordinates.
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* @package
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*/
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Blockly.WorkspaceDragger.prototype.endDrag = function(currentDragDeltaXY) {
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// Make sure everything is up to date.
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this.drag(currentDragDeltaXY);
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this.workspace_.resetDragSurface();
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};
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/**
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* Move the workspace based on the most recent mouse movements.
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* @param {!goog.math.Coordinate} currentDragDeltaXY How far the pointer has
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* moved from the position at the start of the drag, in pixel coordinates.
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* @package
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*/
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Blockly.WorkspaceDragger.prototype.drag = function(currentDragDeltaXY) {
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var metrics = this.startDragMetrics_;
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var newXY = goog.math.Coordinate.sum(this.startScrollXY_, currentDragDeltaXY);
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// Bound the new XY based on workspace bounds.
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var x = Math.min(newXY.x, -metrics.contentLeft);
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var y = Math.min(newXY.y, -metrics.contentTop);
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x = Math.max(x, metrics.viewWidth - metrics.contentLeft -
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metrics.contentWidth);
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y = Math.max(y, metrics.viewHeight - metrics.contentTop -
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metrics.contentHeight);
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x = -x - metrics.contentLeft;
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y = -y - metrics.contentTop;
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this.updateScroll_(x, y);
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};
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/**
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* Move the scrollbars to drag the workspace.
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* x and y are in pixels.
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* @param {number} x The new x position to move the scrollbar to.
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* @param {number} y The new y position to move the scrollbar to.
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* @private
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*/
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Blockly.WorkspaceDragger.prototype.updateScroll_ = function(x, y) {
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this.workspace_.scrollbar.set(x, y);
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};
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